// yt - A fully featured command line YouTube client
//
// Copyright (C) 2024 Benedikt Peetz <benedikt.peetz@b-peetz.de>
// SPDX-License-Identifier: GPL-3.0-or-later
//
// This file is part of Yt.
//
// You should have received a copy of the License along with this program.
// If not, see <https://www.gnu.org/licenses/gpl-3.0.txt>.

use crate::config::{DownloadConfig, PathsConfig, SelectConfig, WatchConfig};

use super::{
    default::{create_path, download, paths, select, update, watch},
    Config, UpdateConfig,
};

use std::{fs::read_to_string, path::PathBuf};

use anyhow::{Context, Result};
use toml::Table;
use bytes::Bytes;

macro_rules! get {
    ($default:path, $config:expr, $get_fn:ident, $key_one:expr, $($keys:expr),*) => {
        try_get!{@default $default, $config, $get_fn, $key_one, $($keys),*}
             .with_context(|| format!("Failed to parse '{}' as a '{}'", stringify!($key_one), stringify!($get_fn)))?
    };
    (@path_if_none $config:expr, $option_default:expr, $default:path, $key_one:expr, $($keys:expr),*) => {
        {
            let maybe_download_dir =
                try_get! {@option $config, as_str, $key_one, $($keys),*};

            let down_dir = if let Some(dir) = maybe_download_dir {
                PathBuf::from(dir)
            } else {
                if let Some(path) = $option_default {
                    path
                } else {
                    $default()
                        .with_context(|| format!("Failed to get default path for: '{}.{}'", stringify!($key_one), stringify!($($keys),*)))?
                }
            };
            create_path(down_dir)?
        }
    };
    (@path $config:expr, $default:path, $key_one:expr, $($keys:expr),*) => {
        get! {@path_if_none $config, None, $default, $key_one, $($keys),*}
    };
}
macro_rules! try_get {
    (@option $config:expr, $get_fn:ident, $key_one:expr, $($keys:expr),*) => {
        $config.get($key_one).map(|val| {
            try_get! {@option val, $get_fn, $($keys),*}
        }).flatten().flatten()
    };
    (@option $config:expr, $get_fn:ident, $key_one:expr) => {
        $config.get($key_one).map(|val| val.$get_fn())
    };

    (@default $default:path, $config:expr, $get_fn:ident, $key_one:expr, $($keys:expr),*) => {
        if let Some(a) = $config.get($key_one) {
            try_get! {@default $default, a, $get_fn, $($keys),*}
        } else {
            Some($default())
        }
    };
    (@default $default:path, $config:expr, $get_fn:ident, $key_one:expr) => {
        if let Some(a) = $config.get($key_one) {
            a.$get_fn()
        } else {
            Some($default())
        }
    };
}

impl Config {
    pub fn from_config_file(
        db_path: Option<PathBuf>,
        config_path: Option<PathBuf>,
    ) -> Result<Self> {
        let config_file_path = config_path
            .map(|val| Ok(val))
            .unwrap_or_else(|| -> Result<_> { paths::config_path() })?;

        let config: Table = read_to_string(config_file_path)?
            .parse()
            .context("Failed to parse the config file as toml")?;

        Ok(Self {
            select: SelectConfig {
                playback_speed: get! {select::playback_speed, config, as_float, "select", "playback_speed"},
                subtitle_langs:
                    get! {select::subtitle_langs, config, as_str, "select", "subtitle_langs"}
                        .to_owned(),
            },
            watch: WatchConfig {
                local_comments_length: get! {watch::local_comments_length, config, as_integer, "watch", "local_comments_length"}
                    as usize,
            },
            update: UpdateConfig {
                max_backlog: get! {update::max_backlog, config, as_integer, "update", "max_backlog"}
                    as u32,
            },
            paths: PathsConfig {
                download_dir: get! {@path config, paths::download_dir, "paths", "download_dir"},
                mpv_config_path: get! {@path config, paths::mpv_config_path, "paths", "mpv_config_path"},
                mpv_input_path: get! {@path config, paths::mpv_input_path, "paths", "mpv_input_path"},
                database_path: get! {@path_if_none config, db_path, paths::database_path, "paths", "database_path"},
                last_selection_path: get! {@path config, paths::last_selection_path, "paths", "last_selection_path"},
            },
            download: DownloadConfig {
                max_cache_size: {
                    let bytes_str = get! {download::max_cache_size, config, as_str, "download", "max_cache_path"};
                    let number: Bytes = bytes_str
                        .parse()
                        .context("Failed to parse max_cache_size")?;
                    number.as_u64()
                },
            },
        })
    }
}